A Study in Magic: The Application
by Books of Change
Summary: The sequel to A Study In Magic. The Wizarding World is convinced of Voldemort's return a year early, but the Dark Lord is neither a fool nor one to let grass grow under his feet. Indeed, he has already started to cull out anyone who can work against him. Will Sherlock, John and Harry hunt down all the remaining Horcruxes in time? Sherlock HP crossover
1. Prologue

**A Study in Magic: The Application**  
by _Books of Change_

**Warning/Notes**: This is the sequel to _A Study in Magic, _which is a BBC Sherlock and Harry Potter crossover AU posted here. The HP timeline and BBC Sherlock's timeline was shifted forwards and backwards to match up. One major BBC Sherlock character's gender was changed for the sake of the plot. Readers beware!

* * *

**Prologue**

The longest day of summer was drawing to a close, and the city of London was humming with excited activity, particularly in one of its dingier streets. There, a crowd of news agency vans surrounded a cordoned-off building like vultures to a corpse. Several cameramen were out adjusting their tripods or mounting their long-lens cameras on them. Those who had their equipment ready were filming the uniform constables standing in attention just outside the yellow tape, or the building where the mysterious shockwave that tore through that part of London and took out the power of an entire city block originated.

Eventually the orange sky darkened to a dusty blue, and by then police were flitting in and out of one particular flat. The mark of an epicenter was in the middle of its living room, plain as day. The flat's windows only had a few lonely pieces of glass clinging to their frames. The rest were out in the streets somewhere, wherever they landed after they were blown off. The wall studs and water pipes were all caved severely outwards, if they remained at all, and bits of chair, table, cups and plates were smashed against the surviving walls, some penetrating through the plaster.

Everything about the scene pointed to a bomb explosion. However, there was no trace of smoke or fire inside the tiny flat. The baffled firemen from the London Fire Brigade said as much to one of the SOCOs on site. An equally baffled bomb technician from the Met added her own expert opinion to the discussion. The walls caved from rapidly expanding air pressure, which implied a bomb. Yet there were no traces of chemicals or gas inside the flat … there wasn't even a hint of laundry detergent! How was this possible?

While the firemen and bomb technicians argued among themselves, two solemn-faced constables moved a body bag on a wheeled stretcher. Newly promoted Detective Inspector Sally Donovan and Detective Chief Inspector Lestrade watched them go, standing side by side. Donovan looked grim yet composed, but Lestrade appeared pale and a bit shaken.

"You knew her?" Donovan asked quietly, after the constables disappeared from view.

"She was the aunt of one of my daughter's school mates," muttered Lestrade. "I met her a few times."

Donovan nodded wordlessly.

The two stood quietly again for a few more heartbeats.

"Will you be alright, handling this?" Donovan asked at length.

Lestrade didn't reply for a blink. Then he let out a deep sigh.

"…Yeah," he said stoically. "Yeah, I'll be fine. Donovan, you take care of the crime scene. I'll notify family."

Donovan made an affirmative noise. Then she joined the SOCOs trying to collect evidence from the destroyed flat.

Lestrade headed out. On his way down, Lestrade made several calls. For the first, he used a black iPhone like any other. For the other calls, he used a mobile phone that was nothing more than a flat, palm-sized glass case that contained burning purple flames. As strange as the latter sight was, none of Lestrade's colleagues seemed to take notice of it.

Lestrade finally got inside his car. There, he put away the glass phone, and retrieved another glass phone that had green flames instead of purple from his inner jacket pocket. He then called out a name:

"Sherlock Holmes!"

-oo00oo-

Miles away from his usual stomping grounds in London, Sherlock Holmes was lounging in a comfortable chair with his feet propped up on a desk and a baby boy snoozing against his chest. The monitors on the desk, which Sherlock was studying lazily, showed John Watson, armed with what looked like an AK-47, chasing a wizard named Sirius Black through a large span of grassy heath.

Sherlock let out an irritated grunt when the mobile phone in his pocket started to vibrate. He silenced it without disturbing the baby on his chest and continued to study the monitors.

The phone vibrated persistently, however. The baby eventually sensed the incoming calls and started to make keening noises. Only then did Sherlock pull out his phone and swipe the virtual bar.

"I told you I'm busy!" snarled Sherlock.

"LV murdered Amelia Bones," Lestrade snapped in reply.

Sherlock put his feet down and sat up straight. His grey eyes gleamed with intense focus.

"I didn't think he'd dilly-dally," he said in a low, rumbling voice.

"He obviously didn't," growled Lestrade. "The Ministry of Magic's handling the case, but media caught wind of it before I got there. Your brother probably knows all about it."

"He's likely discussing counter-strategies with the PM and Secret Service right now," said Sherlock snidely. "I assume this means the next Minister for Magic is going to be Rufus Scrimgeour?"

"Yes, but never mind that. When are you returning to London?" asked Lestrade.

"Why should I?" Sherlock sneered. "You already know who the murderer is—not that you can arrest him!—and for magical cases, there's no difference between me working here or there."

"I didn't think you'd prefer Yorkshire over London."

"I don't," said Sherlock between gritted teeth. "I hate it here. But Benedict still can't sleep when there are cars roaming about and John demanded training time—"

"Didn't think you'd bow to domestic concerns, either," said Lestrade, his grin evident from his voice.

"Shut up!" Sherlock snapped.

Then he paused for a second. The monitors now showed John rapidly gaining on Sirius. Soon John had him face down on the ground with his wand arm twisted behind his back. John's next move was a lightning fast swipe to the left. A silvery cloak appeared out of nowhere and underneath the folds emerged a skinny, white-haired, bespectacled boy who had the pinched, slightly unhealthy look of someone who has grown a lot in a short space of time. The boy—known as Harry Watson to the locals, but Harry Potter to others—put his hands up in surrender when John aimed the faux-AK-47 at him.

"John is done with basic training," said Sherlock, a satisfied smirk on his face. "We can now move on to urban guerrilla warfare."

"Do I even want to know what you two are up to?!" Lestrade shouted.

"No," said Sherlock gleefully.

"What about your baby?!"

"Got him well taken care of," said Sherlock breezily as he got out of his chair. "We'll take the train back to London this evening. Alert Arthur Weasley and the rest. Don't dally!"

And with that, Sherlock ended the call, blithely disregarding Lestrade's furious expostulations. Then he dialed two on his speed dial.

Before long, the monitors showed John Watson pulling out a mobile phone, Harry Potter lowering his hands and Sirius Black shakily getting back to his feet.

"It's time," Sherlock intoned.

Harry seemed to sag a little. Sirius bared his teeth. John merely shrugged.

"'About time."

-oo00oo-

**Final Notes**: And here we go again. Thank you for your patience!

I've taken the time to thoroughly iron out my Plans for ASIM-TA (I already had them, but if you have any idea what kind of detail freak I can be…). I've also spent time working on my original novel, now about half-way done. ;) ;) ;)


	2. Pascal's Wager

**A Study in Magic: The Application**  
by _Books of Change_

**Warning/Notes**: This is the sequel to _A Study in Magic, _which is a BBC Sherlock and Harry Potter crossover AU posted here. The HP timeline and BBC Sherlock's timeline was shifted forwards and backwards to match up. One major BBC Sherlock character's gender was changed for the sake of the plot. Readers beware!

* * *

Chapter One: Pascal's Wager

Harry Potter imagined himself doing many different things when he returned to London, after spending a month in the country. Listening to an old couple talk for seemingly hours whilst trying not to slouch or sigh was not one of them.

"…which wasn't the way I'd put it at all, silly woman," the woman rambled. "Anyway, it was then that I first noticed it was missing. I said, 'Have you checked down the back of the sofa?' He's _always_ losing things down the back of the sofa, aren't you, dear?

"'Fraid so," said the man.

Harry let out a tiny sigh and clawed at the armrests of his leather chair.

"Keys … small change … sweeties," the woman went on obliviously. "Especially his—"

"_Glasses_," the man and woman said, almost simultaneously.

"Blooming things," continued the woman. "I said, 'Why don't you get a chain, and wear 'em round your neck?' And he says, 'What, like –'"

"_Larry Grayson_," the couple said together.

"So did you find it?" asked Harry, his frustration getting the better of him, "Your – lottery ticket?"

"Well, yes, thank goodness. We caught the coach on time after all," said the woman matter-of-factly. "We managed to see, er, St. Paul's, the Tower …"

That moment, the door to the living room opened and a girl dressed for outdoor exercise and had her thick brown hair up in a high ponytail walked in. Harry stared at her in surprise.

"Sorry, you're busy," Julia Lestrade said as she glanced at the grey-haired couple.

Then she blinked as she took in the sight of a man who looked like Sherlock thirty years into the future, and a white-haired woman who had Sherlock's eyes and wore a black jacket with the collar propped up.

"A friend of yours, dear?" asked the woman as she studied Julia with considerable interest.

Harry quickly got to his feet. "It's time for you to go."

"Oh, is it?" said the woman.

"_Yes_," said Harry, as he gestured wildly at the wall clock and the door.

The couple got up from the couch obligingly. Julia jumped out of their way and stood by the table.

"Tell him to ring up more often, will you?" the man said as he took out a white, foldable cane.

"Umm … well …" Harry stuttered.

"She _worries_," said the man, his milky eyes downcast towards the woman's general direction.

Harry sighed. "Okay. Bye."

The woman briefly stroked Harry's cheek before she headed out, an arm hooked around the man's neighbouring elbow. Harry hastily shut the door behind them.

"Sorry about that," said Harry as he leaned against the door.

"No, no, I didn't knock, sorry," said Julia, wide-eyed. "So who were they?"

"They're…"

Harry paused. He didn't know what to call Mr. and Mrs. Holmes. 'Grandma and Grandpa' felt about as awkward as him calling Sherlock 'Dad'.

"…Sherlock's parents," he said eventually.

Julia blinked, "His _parents_."

Harry nodded. "They came with us to be in town for a few days."

"_They_ are his parents," muttered Julia, now looking out by the window.

"Mycroft promised to take them to a matinee of _Les Mis_," sighed Harry, "he'll probably try to talk me into doing it."

Julia exhaled. "Well. That's …" she looked at Harry, then down the window and back again.

"What?" Harry asked, frowning.

"I mean, they're just … so…" stammered Julia.

Harry looked at her.

"…_Ordinary_," she finished.

Harry snickered. "Sherlock says that the cross he has to bear."

Then he went and resumed his seat on the leather armchair. Julia walked away from the window and sat on the red one.

"Looks like you've been running a lot," said Harry, noting the muddy running shoes on Julia's feet.

"Grandpa's been putting me through the paces," said Julia.

"Oh, yeah, how is he?"

"He takes me to Seattle for trail running and then spends the afternoon hiking the Shenandoah Mountains."

Harry squinted.

"Correct me if I'm wrong, but didn't he get _shot_ a month ago?"

"Do you think a gunshot wound can stop him?" Julia huffed. "Mind, he's not a complete monster. He's under doctor's orders to not use magic until he completely heals and he's listening."

"How does he travel to Seattle, then? A broom?"

"Too far, and you can get shot down. Literally," said Julia. "Robert has a wardrobe that takes you to Mt. Rainer."

Harry smiled. "He would. Now what about Ron, Neville and Hermione? How are they doing?"

"Fudge tried to take Ron to court for what happened at the last task of the Triwizard Tournament," said Julia calmly. "But the Wizengamot threw out the case; said he had no grounds for a suit. He's out of the office now."

"Good," said Harry, feeling very vindictive. "What about Hermione?"

"Panicking over O.W.L.s. and the war."

"Of course. I assume Neville's getting harassed by his relatives over the same."

"He hid at my place and Ron's when it got too much," said Julia, lips twitching. "So what about you, did John and Sherlock stuff in you cage and abandon in you in a forest? Where are they, anyway?"

"Out. And nah, I just did a lot of running through grasslands and hills," said Harry, rolling his eyes. "Well, I say _a lot_ … John cut my training in half when I went down with a cold after thirty minutes of running. What's up with alternative magic and running, anyway?"

"If _you_ don't know, how can _I_ know?"

"Your grandfather is the Grandmaster. You tell me," Harry retorted.

"Geezers like grandpa rarely explain; they just tell you what to do and expect you to obey," parried Julia. Then she paused. "Most of my training was endurance training, and it sounds like yours was, too. Since the magic requirement for Dao-ga is a lot higher than mainstream wizardry, I think that's why everyone's pushing you to run."

Harry nodded. Practitioners of Dao-ga— an obscure, dying branch of magic— didn't use wands, but cultivated their magic to the point it saturated their entire body, thus making their own body a wand, to cast spells. The reason why Harry had to learn it was if he could consciously control his magic, he would be able to transfer the soul fragment of Lord Voldemort currently residing in him to someone else if he gave his magic to that person. This was possible because life and magic were intrinsically tied together, so when one gave their _life_ to someone else via blood donation, one gave their magic also.

While many preferred that he, Harry, would give the soul fragment to someone who was on death row or about to die from illness or old age, since the person's death would also mean the soul fragment's death, Harry instinctively knew it wouldn't work as neatly as they thought. For one thing, they would have to _find_ a death row inmate about to get executed, was willing to house a soul fragment of Voldemort, and wouldn't spill the beans to a Death Eater — a tall order for anyone. Yet more importantly, the new receptacle of the soul fragment had to be _human_, _magical_ and _willing_. The only person who met all requirements, and was willing to take something as vile as a fragment of Lord Voldemort's soul, was Dr. Robert Dongyi Ju, husband-to-be of Julia's maternal Aunt, Jacqueline Shin. Harry had been too desperate to refuse the most generous offer. So all Harry had to do was learn Dao-ga.

But therein lay the problem. In order to learn Dao-ga, one had to cultivate one's magic, and the only way to cultivate one's magic was to challenge one's life with _hardship_. Since one of the simplest and most straightforward forms of hardship was physical fitness training, Harry had decided to take that route. However, Harry's fitness level was such that he would find himself emptying the contents of his stomach after a mere thirty minutes of running and then lying in bed the next day with cold-like symptoms.

"Over-training," John declared when this happened for the first time. "We're going to have to dial down a bit…"

"I can keep going," Harry protested weakly.

John lightly bopped his head. "You won't. Not if you want to keep your body intact."

So John switched Harry's training to series of body-weight exercises, short runs (defined as twenty minutes) at maddeningly slow paces, and burpees. The latter usually left Harry flat on the ground, drenched in sweat, muscles aching and cursing the day he was born. It wasn't long before Harry started to notice a pattern. He was fast, but only in short bursts. That was no good, because for Dao-ga, stamina was everything. Yet try as he might, he didn't seemed to be lasting any longer. This pointed to an unbearable, but unescapable conclusion: the greatest weakness of the wizarding world was … Harry himself.

Harry looked down at his knees as the thought hit him hard once more. As usual, the pain was as crippling as the first time.

Julia, who watched Harry quiet down, spoke after a beat.

"You don't have to _run_ to learn Dao-ga," she said carefully. "Grandpa's cultivated his magic through dancing."

That jolted Harry rudely. "That's a disturbing image," he muttered.

"Dancing is required for _Baksu Mudang_. Uncle Jeremy told me grandpa once joined a ballet troupe for—"

"Okay, stop!" Harry shouted as he covered his eyes. "I get it!"

Julia smirked briefly before sobering.

"Why not music? You're pretty good at the violin."

"Not that good," Harry protested.

"You're good enough to audition!" said Julia earnestly. "C'mon, what if—"

"I know, I know," Harry interrupted. "I'm actually going to ask Dumbledore what he thinks about me switching to music."

Julia let out a sigh of relief. "And if he's favourable, no more running?"

"I'll continue," said Harry, "Just not as intensely; hedging my bets and all that."

"That is safer, I suppose," said Julia. "So are you up for a run now?"

"Yeah, sure," said Harry. Then he raised an eyebrow at her. "John asked you to ask me, didn't she?"

"Why else would I come here?" said Julia teasingly before adding, "Seriously, though, I'd like a running buddy. I can't ask Hermione or Ginny 'cause they both think I'm nuts for running at all. I do okay alone, but it gets lonely after the first hour."

"'First hour'; _ha_," Harry muttered as he stood up. Then he smiled wryly as he recalled the talk that made him continue the much despised running…

-oo00oo-

About two weeks into summer holidays, Harry started hiding from John so as to avoid training, which he by then considered a brutal and futile exercise. Sherlock, of course, found him within ten minutes.

"What are you doing here?" he demanded the second time it happened. "Why aren't you training?"

Harry shrugged. Sherlock lifted an eyebrow at that.

"What's troubling you?" Sherlock asked in a low voice.

Harry shrugged again and then looked away. Soon he heard Sherlock exhaled through his nostrils.

"What – is – troubling – you?" Sherlock enunciated.

An awkward atmosphere descended in the room as Sherlock's question remained unanswered. It soon turned to toxic smog like consistency. Sherlock, of course, was entirely unfazed and bore his intense stare at Harry, silently demanding an answer. Harry stubbornly kept his mouth shut as long as he could, despite knowing it was useless.

At last Harry caved.

"I don't know what to do," he said helplessly.

Sherlock nodded knowingly.

"You have a habit letting your intuition guide your decision-making," he said. "That's only going to leave you paralyzed right now. Instead, think rationally."

"But _how_?" Harry cried.

"Use Pascal's Wager," Sherlock replied.

Harry frowned. "What's that?"

"The famous French mathematician Blaise Pascal defended his belief in God in the following manner," Sherlock explained. "Suppose God doesn't exist. The atheist wins, and the believer loses. If God does exist, the situation reverses. The consequences of being wrong with each belief, however, differ starkly.

"If God doesn't exist, all the devout believer has lost is the opportunity to fornicate, imbibe and skip many boring religious services. And since how you live doesn't matter at all in a godless universe, neither person has lost anything because there is nothing ultimate to lose to begin with. But if God does exist, the atheist roasts eternally in hell. The rational person— at least one who is convinced the Almighty cares about how we behave and what we think— thus chooses to believe God exists."

Harry nodded slowly. He could follow the argument, and the logic was clean. Yet he couldn't help but feel that there was something missing. He also couldn't connect the argument to decision-making, but rather thought it sounded like Sherlock agreed with Pascal.

"Note that I've said nothing whatsoever about my own conclusion on the matter," said Sherlock, a knowing smirk on his lips. "You should also note Pascal's Wager is not an argument for or against the existence of God. It's simply a practical application of statistics and probability."

Harry frowned again. Why was Sherlock bringing up statistics and probability? What did it have to do with his future?

"You have one pressing and unavoidable goal in your life at this moment, and that's defeating LV," Sherlock stated. "You may rationally believe that you will win. If you are certain of this, then preparing for a life beyond the final battle is the correct response to this assumption. But you cannot be sure. There exists the possibility that you may lose. So you must factor this when you decide on how to spend your time.

"If you split your efforts between preparing for the final battle and your life afterwards, and you are wrong and you lose, it won't matter because you will most likely be dead. But if you are right and you do win the war, all you've lost is the chance of having a more prestigious future.

"Now, suppose you spend all your time on battle preparation and you are wrong. Then you're still dead or as good as. But if you win, you are ruined because you've burned all your bridges. Again, suppose you go all in preparing for your future after the battle. This increases your chances of dying, which defeats the purpose of preparing for that future, but you would sit quite prettily indeed if you do survive."

Harry pulled a face. Of course Sherlock wouldn't consider how much he, Harry, would hate himself if he made such a selfish decision as the latter.

"So if you are wise, what would you do?" asked Sherlock.

"Do both?" said Harry, still grimacing.

"Yes," said Sherlock, nodding. "This gets into the heart of your dilemma. Your goal is not maximizing the chances of winning, but rather simultaneously increasing the odds of a good life after the war and minimizing your chances of dying. Now for you, a good life after the war is densely tied to how well you handle the battle, isn't it?"

Harry nodded curtly.

"So your instinct may tell you to pour all your efforts to battle preparation," Sherlock went on. "You'll be stupid if you do. Remember Pascal's wager: what will happen to me if my assumptions are wrong? Preparing for your future after the war is not nearly as costly as going all in on battle preparation."

"But I have to do it!" said Harry furiously.

"Of course," said Sherlock, raising an eyebrow. "You're going to hedge your bets and do both, aren't you? Now however you divvy up your efforts—and I recommend an 80/20 percent split, 80 going to the most important item—you need _time_. The only way you can have time is eliminating anything that is irrelevant to your goal. Your school work and classes are fixtures that take about 80% of your day, but since it covers prep for your future as well as battle prep, you can leave it as is. This leaves you about 20% of extracurricular time. It is here you can make changes. Take, for instance, Quidditch."

Harry felt his heart drop to his stomach.

"Y-you think I should quit?" he stammered.

Sherlock shrugged carelessly, "Unless you were planning to go professional."

Harry swallowed hard as he thought about it. Truth be told, he had fantasies of standing in the middle of a golden Quidditch pitch, wearing England's colours, while Ludo Bagman's magnified voice hollered: 'And I give you… _Potter_!' since watching the Quidditch World Cup last year. However, these fantasies were just that: fancies. He wasn't like Oliver Wood, his old Quidditch House Team Captain, who was now playing for Puddlemere United in their reserve team. Quidditch didn't define his entire life.

"…I should," Harry admitted painfully. "It's not like I can play for more than an hour…"

"So you gain an hour," said Sherlock, smiling in approval. "The next thing to consider is your music lessons."

Harry stared, startled. Both Sherlock and John had been so adamant about music lessons, it hadn't occurred to him Sherlock would actually allow him to quit. He also felt surprised when an intense feeling of regret, quite similar to the one he felt when he thought about quitting his House Quidditch Team, stabbed through his chest. He couldn't understand it; he dreamed of quitting violin. So why did he feel regret?

"Unlike Quidditch, your music lessons are more than just entertainment," said Sherlock. "Through it you have relations with Jacqueline. I was also told music is one of the three venues through which you can learn Dao-ga, which is directly related to battle prep."

Harry sagged. Of course Sherlock wouldn't let him just quit.

"I know you're training for long-distance running to learn Dao-ga," said Sherlock, giving Harry the Look. "You have the temperament of an athlete, so running makes sense. However, it would be foolish to simply discard violin when you've already built two years of experience. You also don't know which option will be more effective. Don't forget Pascal's wager."

Sherlock then bore his piercing eyes into Harry's.

"I'll leave the final decision to you," he said. "Choose wisely."

-oo00oo-

**Final Notes**: Mummy and Daddy Holmes are trying to get better at the business of small talk and pretending to be normal (ha). Harry knows the former (but not the latter), and is trying to honor their efforts ;)

Sorry for the lack of update. These past 2 weeks, I've been running around as though my head's been lopped off after receiving news that I might get laid off/made redundant. I'm using whatever time I have—which isn't a lot, unfortunately— to write this. I've got interview(s) lined, but who knows … I do hope for a good outcome ;)


	3. A Melancholy Birthday

**A Study in Magic: The Application**  
by _Books of Change_

**Warning/Notes**: This is the sequel to _A Study in Magic, _which is a BBC Sherlock and Harry Potter crossover AU posted here. The HP timeline and BBC Sherlock's timeline was shifted forwards and backwards to match up. One major BBC Sherlock character's gender was changed for the sake of the plot. Readers beware!

* * *

Chapter Two: A Melancholy Birthday

About three days had past since Harry Potter returned to London. His friend Ron Weasley was going over the incident reports for the month of June—five rolls of parchment in total— with his twin brothers Fred and George that day. Then his mother burst into his room.

"John just called," she said, waving her phone. "We're going to Baker Street to celebrate Harry's birthday."

"Now?" asked Ron, startled.

"Well, of course!" said mum, raising an eyebrow at them. "His birthday is today, you should know that."

"Of course we do," said Fred. "We just didn't know he was back in London."

"Well, you know now," said Mum sternly. "So clean up this mess and get ready!"

Then she turned and shut the door behind her.

"Our work is just a mess, now, eh?" Ron grumbled angrily. "Let's see if she'll still call it a mess when the customers hurl Howlers at us…"

"Forget it," said George bracingly. "It's not like she understands what we're doing. Besides, it _is_ Harry's birthday; should be fun."

Ron nodded mutely. Fred and George started talking about which Weasleys' Wizarding Wheezes merchandise they should give to Harry as his birthday present soon after. Ron didn't join the conversation, for he was trying to squish the ugly feeling of resentment that rose like miasma at the mention of Harry's name.

Ron knew his feelings were unjustified. It was not like Harry ever demanded special treatment or recognition from anyone, let alone from Ron. It was just … for once, he wanted to be treated like someone special. Wasn't being the director of Zing ®, formerly the Magical Mobile Network (MMN), at age fifteen special enough? Of course, there was that little problem of no one _believing_ that he was …

"You're too quiet," said George, frowning at Ron. "What's wrong with you?"

"Nothing," said Ron tersely, "Just thinking about what to get."

"Didn't you already get him something?"

"Yeah, but on the second thought, I can do better," Ron lied.

Fred shrugged, "Suite yourself. I'm hungry. Let's go grab something."

And with that, he and George Dispparated.

Ron remained in his seat, brooding.

Ever since Fudge tried, but failed, to take him to court, Ron had a suspicion that gnawed on him constantly: the reason the Ministry for Magic didn't bother to arrest him was because they thought he couldn't possibly have a major role in the MMN, thus couldn't be responsible for the MMN debacle. While he was immensely relieved at not having to face judge and jury, he couldn't help but rage at the implications.

Before the MMN, Ron thought becoming as rich as Croesus would make him feel happy and fulfilled. Yet after gaining more wealth than he knew what to do with, Ron found himself still feeling discontent. He was missing something, and that something looked a lot like _acknowledgement._

Maybe … maybe if he became Prefect, people would take him seriously. Maybe then they'd think he was someone worth knowing. Of course, Ron had no hope of getting the badge. He gave up any chance of being named Prefect when he gave his all to the Magical Mobile Network. The only reason he didn't fail out of Hogwarts was Miss Jack's very real threat to sack him if he got marks worse than Poor. And who in their right mind would make him Prefect over _Harry Potter_?

At length Ron let out a heavy sigh.

"This is stupid, and I sound like Percy," he muttered.

Ron let out another sigh. Then he stomped down to the kitchen.

-oo00oo-

Ron and his family—minus Percy; he didn't show his ugly mug in the Burrow since moving out—travelled to Baker Street late in the afternoon, Ron and Ginny via Floo-powder, everyone else via Apparition. Ron arrived there first, and let out a gasp after he stumbled out of the fireplace and caught his first glimpse of Harry since the summer holidays started.

To say Harry looked a bit different was like saying a Blast-ended Skrewt turned cute. Harry's hair was completely white – even his eyebrows were the same shade. He'd also grown quite a bit, but his skin gave the appearance of not catching up; it stretched over his longer frame like old bleached parchment. Harry wasn't wearing glasses, but he wasn't squinting as he was wont to when deprived of them. The only thing that remained the same, more or less, was his attire and eyes: The former a mixture of midnight and black, and the latter still bright green.

More people joined Ron's stunned silence as his family members either stumbled out of the basement fireplace or popped into existence. Ginny looked frankly appalled, and Mum threw her hands over her mouth.

"Oh, Harry, dear…" Mum whispered, sounding aghast.

John, who was standing a little behind Harry, smiled wryly. Harry shrugged.

"It's just a colour change," he said.

"You should've picked a different one," said George. "Red is a good choice. Then we can call you our brother, and no one would be wiser. Happy Birthday, by the way."

The rest of the Weasleys hastily offered their Happy Birthdays to Harry. Ron felt guilty for getting so hung up about Harry's changed appearance. Except for the glasses, all of them he knew had been unfortunate accidents or unavoidable byproducts. Harry's white hair, for example, was the result of him giving his blood to their Defence against the Dark Arts professor, Remus Lupin, to cure his Lycanthropy. One of the side effects of donating blood to someone, at least for wizards and witches, was that the donor's hair turned white (apparently as a symbol of life willingly given away; Ron still couldn't wrap his head around this).

"Thanks," said Harry, after the last person finished thumping his back or shake his hand. "And I did try dying my hair, just so you know."

"Dark colours, mostly," said John. "No one was keen about Harry turning blonde. Well, Sherlock didn't care, but we did. All in all, not worth it: black dyes were either too black or had a weird blue tint. Dark red looked fine, but it freaked out Sirius."

They continued to talk about hair colour options as they climbed up the stairs. Then Fred asked the question that everyone was probably wondering about:

"Why aren't you wearing glasses, Harry?"

"I don't need them anymore," Harry said.

"How come?" asked George.

"I got a Muggle procedure that corrects your eyesight done," Harry answered.

"When?" asked Ron, "And why Muggle and not St. Mungo's?"

"Right after I got back to London, and because we didn't know St. Mungo's offered reliable eyesight correction," said Harry. Then he touched the bridge of his nose, like he was pushing up invisible spectacles. "It still feels weird to be able to see the clock from across the room when I wake up."

"You look better with glasses," Ginny muttered quietly.

"I agree," said John, making Ginny jump. "But I didn't want to risk him losing his sight from shattered glass."

Ron was in a sombre mood by the time they reached the first floor. The door to the living room was closed, but one could hear the muffled sounds of a baby giggling through the wood. Then John held the door the open for everyone, and the noise went up to full volume.

221B's living room looked as it usually did, if one ignored the fact it was extended three times and the table between the windows had stacks of white containers, bottles of drinks, and a large chocolate cake. In the centre of the room stood a white picket fence that reached only up to Ron's knee. Inside the fenced area there was Sirius Black, Harry's godfather, and Jeremy Benedict Holmes, Harry's ten-month-old baby brother. Sirius had his hands outstretched towards Benedict, who was standing on his own two feet.

Everyone gasped when Benedict took a single wobbly step.

"Merlin, he can walk now?!" Dad exclaimed.

"Yep, he's gone mobile," said John, grinning. "Heaven help us."

"When did he crawl?" asked Mum, as she and everyone else crowded around the fence.

"He never did," said John. "Just wouldn't warm up to the concept."

Benedict took two more wobbly steps and then toppled. Ron and his family applauded as Sirius caught him in the nick of time.

"He's growing up so fast," said Mum fondly.

John made an agreeing noise. Then she stooped down and hefted Benedict up. Ron looked around to see who else was there in the calm that followed. He found Sherlock sitting on the leather armchair, open book in hand. Remus Lupin was by the kitchen's sliding doors. Julia Lestrade and Neville Longbottom were occupying the couch. Hermione was absent.

"Where's Hermione?" Ron asked.

"On her way," said Julia, smiling in way that eerily reminded Ron of Miss Jack (or should he call her Mrs. Jack?) "You know London traffic."

Ron didn't, but decided not to remark upon it.

Hermione showed up with her parents shortly thereafter. John opened the food table upon their arrival (yay!). While Ron, his siblings and his friends descended on the food, Hermione's mother and father honed in on Ron's mum and dad. Ron overheard a snippet of their conversation on his way back from the table with his heavy-laden plate.

"Hogwarts is the safest place to be, under the circumstances," Dad was saying firmly. "That's why I'm sending my own children back."

Ron sat next to Hermione at the couch.

"You told your parents about You-Know-Who?" he asked quietly.

Hermione bit her lower lip.

"I had to," she said. "The Ministry sent safety brochures to all households that have at least one witch or wizard, remember? They read it, and wanted to know what happened."

"How did the talk go?"

"As well as you can expect," said Hermione. "We haven't talked about it recently, but I know they still prefer I go to a Muggle Comprehensive and study for the GSCEs. At least until the dust settles."

"Would you?" Ron asked.

"Of course not!" said Hermione indignantly. "I'm not running away!"

Ron smiled.

Unlike Harry's memorable twelfth birthday, this year everyone was content to sit, talk to each other, and partake the good food and drinks, even when Fred and George pulled out the fireworks (they weren't lit; John told them she will not be responsible for her actions if they upset Benedict, and Mum drew her wand at them). Ron, Harry, Hermione, Ginny, Julia and Neville talked about their summers.

"Bill's back at home," said Ron. "He applied for a desk job at the England branch so he could help us out."

"Can't be that exciting, compared to being a curse-breaker," Harry remarked.

"He says he misses the tombs," said Fred. "But there are compensations."

"Like what?" Julia asked.

"Remember Fleur Delacour? She's got a job at Gringotts to eemprove 'er Eenglish—" George sniggered. "—Bill's been giving her a lot of private lessons."

Harry's eyebrows shot up. Then he shared a knowing look with Julia. Ron stole a look at his sister when they did. Ginny looked unmoved, but then again, there seemed to be a strained air about her.

Rain started to lash the windows as the day grew old. A chill started to permeate through the flat, so Ron's mum lit a roaring fire in the fireplace. Ron felt like he'd sunk himself in a hot bath afterwards.

"Oh, this is so cosy," said Mrs. Granger, as she stared at the fire with a steaming teacup in her hand.

"Mmmn," Sherlock rumbled. He then turned to prod John, who was sitting next to him at the couch, fast asleep. He blinked when John didn't wake up.

Lupin came to the rescue.

"Why don't we open presents?" he said, clasping his hands.

Everyone gathered around Harry, holding their wrapped gifts. Ron studied their sizes and shapes, and figured most people got an item in the wish list Sherlock and John sent out. The list made gift-buying easier, but some of the items listed made Ron suspect Harry wasn't the one who created it.

Fred and George presented their gift first: They dragged in a chest that an overlarge red bow tied in the middle.

"Here you go, Harry," said Fred, grinning. "Enjoy."

Harry stared. "Why a chest?"

"We didn't know what you'd need for defence, so we put everything that might be useful," said George.

"_Defence_?" Mum exclaimed, outraged, as Harry untied the ribbon and threw open the lid.

The chest was full to the brim with Weasleys' Wizarding Wheezes products such as Extendable Ears, Self-Propelling Custard Pies, and an impressive number of firecrackers. Sherlock joined Harry at the floor and started pulling out the contents like a child would at Christmas.

"What's this?" asked Harry, holding up a small leather sack.

"Peruvian Instant Darkness powder," said George. "Throw it, and you get instant darkness. Lighting spells won't work in it."

"Interesting," said Sherlock. "So how would you navigate through the darkness you've created?"

"Eh, we were thinking along the lines of throwing it _at_ your enemy, so you can escape," said Fred.

"You should always have a fail-safe for the weapons you make," said Sherlock sternly. "Start working."

Fred rolled his eyes and George shrugged ruefully. "Will do," said the latter.

Harry moved on to his other gifts while Sherlock continued to examine the chest. Hermione's gift was a box of Honeydukes chocolates and a book titled: _Born to Run_ –_ A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen_; Neville, a pot of dittany ("Uncle Algie got it directly from Crete."); Lupin, a book titled: _Practical Defensive Magic and its Use Against the Dark Arts_ ("It's from both me and Sirius"). Even Dobby the house-elf brought a present, which turned out to be – _socks_.

"Dobby is making them himself, sir!" the elf said happily. "He is buying the wool out of his wages, sir!"

The left sock was bright red and had a pattern of broomsticks upon it; the right sock was green with a pattern of Snitches.

"They're … they're really … well, thanks, Dobby," said Harry. Then he pulled them on, causing Dobby's eyes to leak with happiness.

There were four more presents left after Dobby's odd socks, one of which was Ron's. Harry opened the box-shaped one first. It contained pair of black shoes that had thick cushioned soles, a mesh body and silver stripes that reflected light (Hermione told Ron they were for running, which made him incredulous; Muggles had shoes just for _running_? What for?!).

"Thanks, Dad," said Harry sardonically as he held up the shoes. Then he placed them to the side and picked up a hefty-looking parcel that was from Sirius.

"Don't bother," said Sherlock, after putting away the profoundly disturbed look that formed on his face when Harry called him 'Dad'. "It's just high-end Quidditch Gear."

"How do you know that?" Sirius demanded.

"I followed you," said Sherlock.

"I saw no one," Sirius protested.

"That is what you may expect to see when I follow you," said Sherlock haughtily.

Harry opened the gift anyway. As Sherlock said, it contained a trunk of Quidditch equipment: all four balls, with the Bludgers chained to the bottom and the Snitch locked inside an inner compartment; a pair of Beaters bats and polish to clean them. There was also a small mirror.

"It's a two-way mirror," said Sirius. "James and I used to use them when we were in separate detentions."

"This is great," said Harry happily. "So you've got the other one of the pair?"

"Yep," said Sirius. "If you need to speak to me, just say my name into it; you'll appear in my mirror and I'll be able to talk in yours. We have phones now, I know, but it doesn't hurt to have a backup plan."

"I agree," said Lupin. "Anyway, Sherlock, why did you say to not bother with the Quidditch equipment?"

"Yeah, what's up with that?" asked Sirius.

"He's quitting the team," said Sherlock matter-of-factly.

"WHAT?!" Ron, Fred, George, and Ginny shouted.

"You're lying!" howled Sirius.

"He's not," Harry mumbled very quietly, without looking at anyone.

"Why?!" Ron cried. "You love Quidditch! You're the best Seeker I've ever seen! Even Krum's got nothing on you!"

"I'm not, and I really don't want to quit," said Harry miserably. "But I need the time to _prepare_."

A hush fell in the living room after that statement. For a long beat, only the sound of the cackling fire and Benedict quietly whimpering could be heard.

"…Sherlock told you to quit, didn't he?" said Sirius, scowling heavily. "You know, your father would've never let anyone stop him from having fun. You don't have to do everything he says. He's not right all the time."

Harry flinched. Then he turned to look at John, who was still fast asleep.

"How amusing," Sherlock said coldly.

"What is?" demanded Sirius.

"You," drawled Sherlock. "Dumbledore will be quite pleased to know that you and Snape, for once, are in agreement."

Sirius drew out his wand furiously.

"_Stop it_!" said Harry, jumping in between the two men. "No one's forcing me! I thought about it, and made up my mind on my own!"

"But he's influenced you!" growled Sirius. "He's turning you into someone you're not! You—"

"Sirius, this is not the time," Lupin interrupted.

"But Remus…!" Sirius started to protest.

"_Padfoot_!" said Lupin sharply. "Sit. Down."

Sirius sat down.

There was an awkward silence. Ron shivered as the chill within the group seemed to seep into the very atmosphere, despite the lit fire.

Harry walked over to John and nudged again. Then he flicked his eyes at the fire, which seemed to diminish before their eyes, and a look of horrified realization dawned on his pallid face.

"Dementors…!" he whispered.

"What, here?!" Dad exclaimed. "But that can't be! Not here in—"

Harry shot out of the flat, wand drawn, ignoring all protest. Ron followed after him.

Heavy downpour was battering the pavement outside, and Ron soon found himself drenched. Heedless of the wet and cold, Harry cast his eyes about, searching the dark streets determinately. Ron wondered how Harry could see anything, as all the street lights in the vicinity were out.

Suddenly, as though sensing something, Harry looked up. Ron looked up, too, and saw, very dimly, a crowd of tall dark shadows hovering on the roof of 221B.

Ron felt his heart jump to his throat when the shadows fell upon them like a nightmare.

Then he was falling … endlessly falling … in cold, mind-numbing despair…

But then he heard someone yell:

"_Expecto Patronum!_"

-oo00oo-

**Final Notes**: Thank you everyone for your well-wishes and patience. I did get laid off/was made redundant (hazards of government contract work, alas), but found employment before the month was over. My new commute is awful and I haven't fully settled in yet, so I'll be updating on a monthly basis until further notice…


	4. Thoughts on Sleep

**A Study in Magic: The Application**  
by _Books of Change_

**Warning/Notes**: This is the sequel to _A Study in Magic, _which is a BBC Sherlock and Harry Potter crossover AU posted here. The HP timeline and BBC Sherlock's timeline was shifted forwards and backwards to match up. One major BBC Sherlock character's gender was changed for the sake of the plot. Readers beware!

* * *

Chapter Three: Thoughts on Sleep

John Watson didn't dream.

To be more specific: John so rarely dreamed that the occurrences of thereof were worth remembering, even if the dream itself was usually forgotten.

Therefore John was quite surprised when she found herself in a middle of a dream and being perfectly aware of the fact on the evening of Harry's birthday. _So is this what lucid dreaming is like?_ John wondered with detached amusement, as she surveyed the landscape.

The setting was Baker Street, and John was hovering several feet above the rooftops, facing the pavement below. It was hard to make out any of the buildings beyond 221B, for a thick grey fog covered the entire area. There was also a strange swirling darkness that seemed to encroach upon the peripheries of John's vision. _Am I a ghost here?_ John mused as she made an attempt to move, preferably fly. But all John could do—if one could call it that—was rise higher. _Figures I can't do what I want, even in a lucid dream, _John grumbled as she rouse sky-ward.

John continued to float towards the heavens like an untethered helium balloon. Then suddenly, her ascent stopped. A silvery lion of impossible size burst through the smog, which receded like a reverse shockwave. The ominous darkness vanished as well. John caught a glimpse of Baker Street, now several hundred feet away, from the clearing, and several moving dots on the pavement. Then the lion filled the entirety of her vision like a shining full moon.

The first impression John had of the beast was that it was unspeakably beautiful and magnificent. The ones that followed were 'terrifying' and 'untamed'. Inexplicably, John wondered what would happen if the lion shook his mane. Then the lion opened its jaw, grabbed John by the cuff and dove.

Then they were free-falling. John didn't feel the wind or rain as the ground approached rapidly. The dots on the pavement proved themselves to be people, one of which was Harry. He had his wand pointing to the heavens. He also looked drenched; his black hair was plastered all over his pale and wet face, his glasses were fogged up and his lips were blue.

_Harry, go back inside, you're going to catch your death, _John thought, alarmed.

Everything turned pitch black as soon as the thought passed. John felt startled at the abruptness of it, and wondered why her subconscious brought this about.

Then …

…John blinked awake. Her heart was pounding as though she'd just escaped a firefight, and her limbs felt heavy. A crowd of freckled red-heads were gathered close, and most of them looked as though they'd just returned from a swim at a pool. The person closest to John was a white-haired boy who has green eyes. He was staring at John with acute desperation if not outright despair.

John stared quizzically at the white-haired boy, and thought she should know his name and wondered about her brains.

"Who…?" John started, and felt intense remorse the minute the word was out of her mouth, because the white-haired boy was Harry, who, of course, reacted like John had stabbed him in the chest

"STOP IT!" he roared, a splash of red flaring on his cheeks and his eyes brimming over in an instant. "THAT'S NOT FUNNY! WHY'D YOU SAY THAT?!"

"Sorry, Harry," said John, feeling like a contrite murderer. "Mummy brains."

Harry was neither amused nor convinced, however. He jumped to his feet and started breathing rapidly, like he was hyperventilating. Soon he was clawing at his hair—so _white_; John was never going to get used to it—and before long, the air in the living room started to crackle as though full of static.

John looked at Sherlock. They shared a brief look and a nod. Then Sherlock picked up Benedict and turned to their guests.

"Get out," he told them.

"…What?" said Arthur, looking and sounding astounded.

"Leave. Now," Sherlock ordered, shooing everyone towards the door.

That moment, the cow-head lamp burst into flames. Hermione's parents took their daughter and fled the room, after giving Harry a look of horror. The Weasleys, Julia and Neville left after them. John saw the look of understanding and anguish on Molly Weasley's face and felt a rush of sombre gratitude.

Sirius lingered, despite Remus' urging.

"Is this—?" said Sirius, dragging his feet, making John wanted to punch him. Hard.

"We need to go," said Remus, pulling at his friend. "Let them handle it."

Sirius gestured at John, the well-meaning prat. "But what about—?"

Remus shoved Sirius out to the hallway. Immediately Sherlock stepped over the threshold and shut the door behind him. Not a moment too soon, it turned out. A phantom explosion left a huge crack on it.

John let out a long sigh and braced for what was to come…

-oo00oo-

"What was that?" Hermione heard her mum demand as soon as the door shut behind them. "What's going on?"

Unsurprisingly, Sherlock ignored the question and marched into his room, Benedict blinking in his arms. He only started to cry when Sherlock slammed the door.

Mr. and Mrs. Weasley shared a rueful look in the quiet that followed.

"After the war… well, a lot of people had trouble coping, especially young ones who lost parents," Mrs. Weasley explained, at last. "Arthur and I housed a few ourselves … they'd bottle up until they couldn't and then, well…"

She gestured at the door, where the sounds of muffled explosions could be heard. Neville looked down at his lap, and Mr. Weasley patted his shoulder sympathetically.

"I guess the magic makes it more … outwardly manifest," said Dad, looking very distraught as he was wont to when he felt guilty. "And I suppose … John and Sherlock lived through a lot of … _that_, especially in the early days when they … uh, didn't know magic existed."

No one said anything in response to the largely rhetorical question.

Hermione supposed no one possibly could.

-oo00oo-

Harry calmed down in ten minutes, after which he was a picture of mortification. John reassured him that his dignity was intact, and then told him hiding inside the cleaning supply closet would undermine any of his future efforts to keep it that way. Sherlock texted John as soon as the crumbling plaster settled:

_Good? SH_

"Let's go get some non-prescription glasses tomorrow," John said as she replied: _Good. Let everyone in._ "Ginny had a point—you look much better with them."

"I'll look like a hipster," complained Harry, scrunching his face. "So you're not worried about me losing my eyes from shattered plastic frames?"

"Wizards probably invented Unbreakable Charms to protect their hipster glasses," John reasoned. "It can't be anything else. Just look at Dumbledore's."

Harry snorted. He then took a deep breath and sat straight as John walked over to open the door.

"Excellent, are we carrying on?" said Fred Weasley brightly as he bounded in, his twin George skipping behind him.

"Yep, round two," said John, smirking fondly at the two.

"In your dreams," said Sherlock haughtily as he sauntered in, a flailing Benedict in his arms. He quickly transferred their baby to John, who cuddled him under her chin, murmuring: "Yeah, yeah, sorry, baby, you'd think your daddy would've learned by now…"

Sherlock sat on his customary chair like a king seating himself on his throne before his lowly subjects. He even did his fingertips-touching-in-front-of-his-face pose to complete the image. _Vain and theatrical twat_, John thought.

"I might as well give a summary of things," Sherlock intoned. "It will assure all of you, I'm sure."

Everyone turned to listen, some despite the instinct to curse him to oblivion, like it was no doubt the case for Sirius.

"His Majesty Holmes is letting us hear his address," Fred whispered loudly.

George pretended to tear up. "I feel so honoured."

John swatted them. "Shut it, you two. His Highness is speaking."

Sherlock gave the three of them an ugly look before continuing:

"That Dementor attack was a sortie," he began. "One designed to gather information and see how we would react. All things considered, the attack ended in our favour, almost embarrassingly so."

John let the pause draw out for a beat so Sherlock could have his dramatic moment.

"How?" John asked, at last.

"The most reasonable response to the attack is the adult wizards taking care of the situation," said Sherlock. "That means you, you, you or you—" he waved at Arthur, Molly, Remus, and Sirius, "—or a combination of you, facing the Dementors. If you managed to fend them off, LV still gains something because you would be left shaken and wondering if it will happen again. If you failed, all the better for LV. But that's not what happened. _Harry _was the one who figured it out and drove them away."

He nodded at Harry, the tiny upturn on the corner of his mouth the only hint of how immeasurably proud he was.

"Now consider the purpose of the sortie," Sherlock went on. "LV wanted to gain intelligence. Why? His goal is becoming the ultimate wizard, one who is immortal and omnipotent, with all of humanity grovelling at his feet. For that he needs to destroy Harry Potter in a very public manner. But he won't do it lightly, not after what happened at the Ministry of Magic."

"Because what happened there ruined the undefeatable image he's trying portray?" Mrs. Granger guessed.

"Obviously," said Sherlock, nodding at her in approval. "He will take precautions. He will also try to find out where we are weak. Speaking of, he is probably beating himself in the privacy of his own mind for his weakened state. We know what or who he will blame for it."

_His missing soul jars_, John thought, but didn't say aloud. Everyone else murmured something about Harry's blood, which John expected.

Albus Dumbledore had explained to everyone LV used the worst possible blood to resurrect himself: Harry's blood, willingly given. The blood was a shared secret because the kids were there when Harry deduced the reason why LV was trying to kidnap him on the sly during the Triwizard Tournament. The soul jars—Horcruxes—were not.

Sherlock and Dumbledore, for once, agreed that they should keep the subject of Horcruxes on a strict need-to-know basis, considering that their destruction was the crux of their offensive manoeuvre. Among those present, Harry, his closest friends, Sherlock, and John were the only ones in the know. In all honesty, John would rather no one else did. LV's mind-reading ability didn't exactly make things easy to have shared secrets, and John would rather shoot her own children than compromise anyone's life.

John hoped they could find all the remaining soul jars, however many there were out there. Dumbledore guessed six, since seven was a magically significant number, and with six soul jars, LV would be a seven-part soul. John found it assuring that out of the potential six, three had already been destroyed. LV's diary, Harry burned with Basilisk's poison. The antique and historically significant cup and ring, which LV also turned to soul jars, Dumbledore and Grandmaster Shin found and destroyed. Whether LV knew about all this, didn't matter. He must believe some of them were no longer available, since Snape told him about the Diary.

"Considering this, what would LV do?" Sherlock asked.

"Make himself stronger?" said Hermione, looking terrified.

Sherlock twirled a finger to show her she was close, but not quite.

"Stop himself from getting weaker," said Harry grimly.

Sherlock nodded. "Good defence is good offence and vice versa. LV knows some vital cards are still available for him for the taking, because if they weren't, he'd be dead."

"So what should we do?" asked George eagerly. "We want to help."

"_George_!" exclaimed Molly.

"Boys," Arthur protested. "This can be dangerous …"

"C'mon, Dad, this is important and Sherlock wouldn't let us listen if he didn't think we can't," Fred argued.

_Not exactly assuring_, John thought, while Molly swelled with motherly rage.

"And I won't ask them to do something that will put them in mortal danger," said Sherlock soothingly. "I'm a parent, too."

_Still not assuring,_ John mused, as she thought about the things Molly and Mrs. Granger raked them over the coals for.

"Safety is an illusion," Sherlock argued. "The current situation is only highlighting the fact. You cannot rule out the possibility LV will use some of his followers' children to plan and execute an infiltration to Hogwarts. And why not? They're readily available as students."

The Grangers turned white, and Molly Weasley gasped.

John sighed, "Could've argued that better."

"I was telling the truth," said Sherlock defensively.

"Yeah, but now the mums are seriously thinking about pulling out their kids," said John.

"We're not running away!" the school-age Weasley children, Hermione, Julia and Neville shouted indignantly, making Arthur do a major face-palm in defeat.

"So you want us to spy on the Slytherins?" asked Ron. "I reckon Malfoy would act as the leader, even if he actually isn't!"

"Don't assume," said Sherlock sternly. "LV can just as easily use someone else to do the job. He won't care who as long as it gets done. That is, _if_ he is thinking to infiltrate Hogwarts."

"So you need us to keep an eye on Hogwarts," said Julia sensibly.

"Obviously," said Sherlock. Then he gave Harry the Look. "Again, don't assume LV will plan an attack just because I said so. Remember his purpose."

The children nodded—all except Harry, who was frowning slightly as he tried to figure out what Sherlock was hinting at.

It wasn't long before a look of epiphany dawned on his face. It made John sigh wistfully.

_You've only just turned fifteen and you're already light years ahead of thinking Sherlock's thoughts after him_, John thought. _When did this happen?_

John continued to bask in the second-hand admiration directed towards Harry as he directed the troops afterwards. His presence and words seemed to assure the Grangers and Weasleys more than Sherlock's did, for there was no hint of reservation when they left.

Lestrade stopped by to pick up his daughter a few minutes after that. He looked like someone thoroughly abused by bureaucracy when he entered.

"Heads up: the MM is looking for an opportunity to see you, Sherlock," he said.

"He shall look in vain," said Sherlock dismissively.

Lestrade growled at Sherlock for making his life even more complicated, presumably. Julia rolled her eyes at him and then pressed a toy jeep into John's hands.

"Grandpa told me to give this to you," she said. Then she herded Lestrade out of the flat.

There was moment of sudden stillness after the door shut behind them.

"Bed," said John to the remaining residents.

"It's still early," Harry protested.

John shook her head firmly. "You just fought soul-sucking, joy-eating monsters. _Bed_."

Harry huffed. "_Fine_," he grouched.

"You raised him well," said Sirius while Harry stomped noisily upstairs. Then, apparently feeling embarrassed, he hurried downstairs to his own flat.

John and Sherlock took Benedict to their rooms. Sherlock and Benedict, rather incredibly, went out like a light.

John stayed awake. The evening nap, which Sherlock deduced as Dementor-induced, managed to mess up her already discombobulated sleeping schedule. John worried about her levels of zombification come morning as she stared at the ceiling.

John was finally feeling a bit drowsy when the door to the room creak opened a sliver. John glanced at the narrow opening without turning. She saw white hair and a pale face.

_So grown up, and yet not quite…_ John thought sadly.

-oo00oo-

**Final Notes**: Sorry for the short update. The good news is things are going back to its previous state, more or less.

I had planned to put some hints of the Marriage Story here, but in the end it didn't work out. Now I'm thinking about publishing the Marriage Story ™ in comic form, since it came to me as series of pictures. A good way to revamp my very dusty LJ/blog and show how John looks like, I think…


	5. The Name of the Game

**A Study in Magic: The Application**  
by _Books of Change_

**Warning/Notes**: This is the sequel to _A Study in Magic, _which is a BBC Sherlock and Harry Potter crossover AU posted here. The HP timeline and BBC Sherlock's timeline was shifted forwards and backwards to match up. One major BBC Sherlock character's gender was changed for the sake of the plot. Readers beware!

* * *

Chapter Four: The Name of the Game

In the days immediately following his birthday, Harry often found himself alone in 221B with only Benedict for company. Mycroft had relocated Mrs. Hudson to an undisclosed location for an indefinite holiday ("She is enjoying herself immensely," was all he would say). Sherlock kept Sirius extremely busy, sending him all over England and beyond. In the meantime, he would vanish with John for long hours in various disguises (most often as an old couple that looked disturbingly like Mr. and Mrs. Holmes). Even Remus all but moved back to Hogwarts as the start-of-term date drew closer. All in all, Harry was left feeling like a disgruntled and lonely nanny as he fed his baby brother, cajoled him to sleep or changed his nappy for what felt like the hundredth time.

Sirius eventually declared temporary mutiny and parked himself in 221C for a half-day. Thus Harry was able to get some info out of him.

"I've been doing a lot of tracking," Sirius groaned tiredly as he poured some Firewhiskey into a glass. "People who vanished after LV returned, who looks like they were taken away, and so on."

Harry knew better than to ask who the victims were. He wouldn't know who they were, and Sirius would get in trouble if he discussed them at length. So instead he asked:

"What kind of people is he targeting?"

Sirius took a long drink, and then slammed his glass down on the table.

"It's hard to say," he said, at last. "I see no rhyme or reason to the disappearances. I mean, people like Amelia Bones make sense. So does Igor Karkoroff. But then we have perfectly ordinary people like Florean Fortescue missing."

Harry stopped short at that.

"Florean used to give me free sundaes. So he's gone too? What happened to him?"

"Dragged off, by the look of his place," said Sirius.

"Why?"

"Who knows? He must've upset LV somehow. Or perhaps he knew something," Sirius took another drink. "He was a good man, Florean."

It was hard not feel morose after receiving such news. Harry was severely tempted to visit Diagon Alley to see how bad things were, but then he would have to bring Benedict along, and he couldn't bring himself to put his baby brother at risk (Harry had a stinking suspicion Sherlock was counting on him to make this decision).

So the days went. Then one morning, Harry had a rare occasion where all of the Baker Street residents sans Mrs. Hudson were at home. So he asked Dobby for a special breakfast. Whereas the elf was more than happy to oblige, Benedict was not so cooperative. He cried relentlessly as John and Sherlock tried to convince him: no, they hadn't abandoned him; yes, they were his parents; and sorry, baby, we won't do this again (John was the only who said this). In the end Harry, Sirius and Remus relocated to 221C in a rather transparent attempt to avoid the screaming.

Harry had just finished pouring the coffee when he heard a tapping noise. The three of them looked up and found an official looking owl, a handsome tawny, bearing the Hogwarts' crest, tapping its beak against the egress window.

"Finally!" Harry exclaimed as he got up. "I was wondering if mine got lost or something…"

Sirius opened the window, and the owl flew inside. It landed on the table, and then stuck out the leg that had a thick parchment envelope tied to it. Harry blinked curiously at the small bulge on the envelope as he reached out to untie it.

Remus offered the owl some water on a dish as Harry broke the wax seal on his letter. As soon as he opened the flap, a silver badge dropped out of the envelope and landed in the jam pot. Sirius used a fork to fished it out, and then put it on a napkin. Despite the sticky black currant jam coating its edges, it was hard to miss the large 'P' engraved on the surface.

For a long moment, Harry just stared at the badge, which glinted under the dim morning sun. His mind felt curiously blank, while at the same time his heart fell into turmoil. He had a sense that he should feel happy, but all Harry could manage was mild irritation as he thought about how much the badge was going to cost him in terms of time. It was as though he'd traded in one enjoyable activity—Quidditch—in exchange for something that only promised drudgery.

"Congratulations," said Remus, at length. "You're a prefect."

Harry nodded.

"You don't look too happy," Sirius remarked.

"I wasn't expecting it," said Harry honestly.

"Who did you expect to get it, then?" asked Remus.

"Hermione," said Harry, without reserve. "Other than her… uh, I guess I didn't really think about it…"

"Ah, well," said Sirius airily. "I suppose it's natural you aren't impressed. James and I weren't prefects either. That honour went to Remus."

"Yes, for all the good it did," said Remus ruefully. "I think the teachers were hoping I'd exert some positive influence over you two. Needless to say my efforts ended in abject failure."

Harry smiled wryly, but said nothing. He would never admit it aloud, especially in Sirius' earshot, but he secretly felt buoyant whenever he knew he was different from James Potter. _Bully _was one of the first descriptions Harry got of him, and to this day no one said anything that suggested he that wasn't. Harry knew he shouldn't put too much weight in Snape's words, considering the source, but the compliments he received for his Quidditch skills, particularly in reference to James' own Quidditch talent, had the curious effect of substantiating the 'arrogant athlete' assessment of his biological father's character. _If an arrogant athlete, why not a bully?_ A nasty voice in his head would ask. Sirius and Remus freely admitted that James was a troublemaker—in the sense that he sought it out—and that disturbed Harry in ways that he couldn't put into words. True, Remus said James continued to be good friends with him after learning he was a werewolf, but people could be friendly to those they happened to like, but be cruel to those they didn't. Weasley twins, case in point.

"Well, what's done is done," said Sirius with mock-resignation. "Let's tell his Majesty the good news, shall we?"

Harry snorted. The idea Sherlock would consider him being made Prefect as good news was absolutely ludicrous. Indeed, when Remus showed John and Sherlock Harry's prefect badge, Sherlock clicked his tongue and scowled.

"A _prefect_. Dumbledore made you a _prefect_," he muttered in an angry, rapid-fire fashion over Benedict's wailing. "What was he thinking? You'll waste valuable time following stupid orders and doing housekeeping, as if you haven't enough to go on … Only someone who has delusions for prestige or change would want the job!"

Sirius and Harry grinned at each other. Meanwhile, Sherlock continued to rant:

"What could you possibly get out of this? Roaming stupidly about in the name of patrolling, sitting in useless meetings, breaking up prepubescent fights or … Oh. _Ooooh_, that's actually brilliant. No, that was _obvious_. Stupid, so stupid. Clearly I need some air."

Before Harry could make sense of the abrupt turnabout, Sherlock shoved Benedict into his arms.

"Congratulations," said Sherlock, oozing insincerity. "Let's celebrate the occasion."

"Oh, great, I wasn't sure it was something to get happy over," said Harry sarcastically.

Then there was a sudden pause, during which everyone realized Benedict was NOT crying, and was in fact making happy burbling noises.

"Where is your Hogwarts letter?" Sherlock demanded.

Harry flapped the parchment letter he was holding like a Tyrannosaurus holding an armful of laundry. Sherlock extracted it from his grip in a flash.

"Pick up food on your back," said John as Sherlock pushed Sirius to the door, his protests notwithstanding. "We'll text you what we want."

Then the door shut, and soon Harry found himself standing quietly with John, Remus and his baby brother. No one said anything until Harry realized the warmth he was feeling wasn't merely Benedict's body heat. He looked down and saw the long wet patch on his shirt-front and the puddle beneath his feet.

Harry glared at Benedict, who was nestling contently in his arms.

"You … little … _prat_," he growled. "You cried on purpose to get back, I just know it."

Benedict gave Harry a gap-toothed grin. Remus quickly turned away, shoulders shaking, and John palmed her face.

"You understand what I'm saying, don't you?" Harry went on, eyes narrowed. "You probably know how to talk already. You just babble because you don't want your baby status revoked."

Benedict giggled. Harry let out a gusting sigh.

"Prat."

-oo00oo-

Remus mopped Harry up as soon as he got his laughter under control. Benedict let John hold him in the interim, and once Harry was clean, he started shrieking if anyone so much pretended to take him away from his mother. Harry had to shake his head at his baby brother's fickleness.

Harry and John sent texts asking for ridiculous things like Dragon rib-eye steak between requests for chips, Chinese and Pad Kee Mao while they waited for Sherlock and Sirius to return. Harry had to wonder how seriously the two were taking these requests, because they didn't reply back.

Sirius and Sherlock returned about an hour later. An enormous quantity of things spilled out of their enchanted shopping bag: books, potion ingredients, quills, parchment, sticks that looked suspiciously like dynamite, several very sharp knives and a container that held five juicy steaks (Both Sherlock and Sirius refused to admit which animal it came from).

"That doesn't look like stuff I have to bring to school," Harry remarked.

"Don't be stupid, of course they are," said Sherlock. "Call it insurance."

Harry squinted at the sticks of dynamite and tried to picture him using them. All he could manage was recall many scenes from Classic Looney Toons, particularly those involving Wile E. Coyote.

"Are you expecting me to train him on how to use those?" asked John, eyes narrowed.

"At the very least enlist an explosives expert who can," said Sherlock breezily. "You know a few, don't you?"

John scowled. "What exactly are you planning?"

"Harry, you explain," said Sherlock, waving.

Harry gaped at Sherlock for a second before he regained his composure.

"Eh, LV wants to shore up his defences and offenses," said Harry slowly. "Besides targeting certain people, he might want something. The question is: Does Hogwarts have something LV might want?"

"Good," said Sherlock approvingly.

"We don't know what LV wants," Harry went on. "If we did, we wouldn't be having this discussion. But it's better to assume there is _something_. Hogwarts is known as one of the safest places in the world, meaning people would want to put stuff there for safekeeping; and the consequences of not making that assumption are costlier than making it."

John nodded in agreement.

"Now we have to ask _how_ LV would get what he wants in Hogwarts," said Harry, warming into his reasoning. "I think he'll use an agent."

"Yeah, his MO is let his grunts do the hard work until it becomes obvious they can't do it," said John. Then she chuckled. "You'd think he'd know better by know, given his track record. Good for us, I suppose."

Harry smirked as he recalled Quirrell and Barty Crouch, Jr. Both had not been particularly successful in carrying out an inside-job in Hogwarts. Though for Crouch, Harry thought as his smile faded, it had been too close and costly.

"So we're back to sniffing out agents again," said Sirius.

Harry shrugged his shoulders, "Can't help it if LV decides to be predictable."

"Aren't you being a bit too nonchalant about this? Your safety is at stake," Sirius pointed out.

Harry was thinking this was rich, coming from his godfather, who'd recklessly broke out of Azkaban to commit the murder he got imprisoned for, when Sherlock asked coldly:

"Do you actually have an idea that will help us figure out what LV is up to?"

"No," said Sirius.

"Then continue to keep your silence until _we_ figure that out," Sherlock snapped.

Sirius whipped around furiously, but before he could do anything, John slammed her mug on the table, hard enough to send the tea in it flying. Everyone stared, including Benedict.

"All right, girls," John said in a deadly calm voice. "I understand that you lot aren't fighting because you're angry at each other. You lot are fighting because there's a war going in, which leaves little room for error, but high levels of uncertainty. All this makes you very tense and stressed. I can't be angry at any of you because I understand your motives and I sympathize with them. But instead of all this fighting, we can have a calm and sober discussion about our feelings and by doing so—"

"Oh, shut up!" Sherlock shouted as Harry and Sirius cringed. "You've made your point three sentences ago!"

John smirked, and then brought her mug to her lips.

"Moving on, then," said John. "Would it help to imagine what LV might want? A crown that makes you smarter? A wand that makes you undefeatable?"

Sherlock rolled his eyes and let out a long, aggrieved sigh. "Do be serious, John."

"I was totally being serious. Anyway, you mentioned the possibility LV might want to infiltrate Hogwarts in large scale. I can picture him ordering the assassination of, say, Dumbledore."

Sherlock nodded. "Even if he didn't have what he wants, Dumbledore's demise, particularly in the hands of LV, will be a catastrophic blow the Wizarding World may not recover from … At least, not quickly enough. So, too, is yours," he added, jerking his nose at Harry's direction.

There was drawn, sombre pause.

"Needless to say, we have a great deal of skin in this game," Sherlock continued. "Thankfully we have experience sniffing out LV's agents in Hogwarts, and have tools that make the job less daunting."

Harry nodded grimly as he cast his thoughts to the Marauder's map, his own 3D map of Hogwarts (which gave him real-time visuals of people), and all the ways Lord Voldemort's previous agents had used to infiltrate Hogwarts: Polyjuice potion infused with hairs from people who had the same name as the agent, secret passages, portkeys, outright possession …

Harry felt his heart thumping as he remembered just how difficult it was to detect people under magical disguise. Would he be able to do this? One mistake and LV might…

"Don't forget your friends," said John. "You've got people who will stick with you thick and thin."

Harry had a blank moment as he digested this.

Then he felt his heart swell as he thought about Sherlock, John, and his friends at Hogwarts … Ron and Hermione, spending hours, days and months with him trying to find the thief after the Philosopher's Stone; Neville and Julia, with him in the Chamber of Secrets; all of his friend helping him through the years… now Sirius, Remus, the Weasleys…

"Sentiment," Sherlock sneered. "But you made your point: We have a fighting chance. Let's use it wisely."

"Sure," said John. "Now let me ask: how exactly is dynamite supposed to help? I suppose you can always use it to blow up a hole in a wall, but wouldn't that make their job easier?"

"John, use your imagination. Harry can throw it _at_ them if or when they infiltrate…"

The meeting adjourned after some heated talk over details and battlefield psychology. Harry's messenger bag had an alarming number of required items by the end of it. Harry was just relieved he didn't have to carry sticks of dynamite in person … at least he thought he didn't have to. Sherlock didn't mention them again, and John point-blank refused to teach Harry how to use explosives (or guns … or grenades … or rockets…).

Then Aunt Harry showed up at their doorstep the next day.

Harry had seen Harriet Watson, John's sister, only once in person. A few days after the Internet Grapevine heard the news Dr Watson (companion of Sherlock Holmes, the 'Net detective) had adopted a child, a woman who looked like a much bigger and older version of John showed up in 221B. Harry's few memories of the incident was a feeling of horror as he listened to the foul language pouring out of the Watson sisters' mouths.

John gaped at Aunt Harry for a stunned second when she opened the door. Then John tried to slam it shut. Aunt Harry easily caught the door, threw it open and pushed herself in.

"You've been involved in some pretty major shite since we've last talked, haven't you Johnny?" Aunt Harry said impassively.

"Manure's about to hit the ventilation system, yeah," John snarled.

"Thought you'd settle down after having a baby. Congratulations, by the way."

"Thanks, I guess. And ha, I wish."

Aunt Harry snorted. Then she looked at Harry.

"Ready to blow some sh!t up, kid?"

Harry gulped.

-oo00oo-

**Final Notes**: This past month was a demonstration in Murphy's Law. I had trouble brewing at home as soon as trouble at work started to subside a little. Specifically, I had a family of wildlife taking residence inside the chimney. Once THAT was resolved (took 3 weeks and a lot of $£¥€), all of the SMEs (Subject Matter Experts) of the project I'm working for were terminated without warning. To top it off, the thumb drive I store my writing—like ASIM-TA—experienced catastrophic disk failure and all files there were lost. Thankfully I had backups.

In short, writing was hard and scarce… I'll be implementing a more comprehensive Backup and Disaster Recovery plan to ensure minimum story loss. Speaking of which, the original novel survived the catastrophic disk failure, and the draft is now roughly 75% done.


	6. Explosive Ordinance Disposal for Wizards

**A Study in Magic: The Application  
**by _Books of Change_

**Warning/Notes**: This is the sequel to A Study in Magic, which is a BBC Sherlock and Harry Potter crossover AU posted here. The HP timeline and BBC Sherlock's timeline was shifted forwards and backwards to match up. One major BBC Sherlock character's gender was changed for the sake of the plot. Readers beware!

* * *

Chapter Five: Explosive Ordinance Disposal for Wizards

Much to Harry's surprise, John let Harriet Watson take him away from Baker Street without another word of protest, even when they realized Aunt Harry's mode of transportation was an ancient motorcycle. Harry wondered about this until he realized Aunt Harry was NOT taking him to some place obvious like Battersea Station, but rather the outskirts of the very rough side of London.

Aunt Harry eventually stopped in front of a condemned building so dilapidated not even homeless squatters appeared to have bothered with it. There was so much overgrown greenery around the building's perimeter it looked as though it was situated in the bush. The moment they stepped inside the smell of rotting urine punched Harry in the face. Eyes watering, Harry wondered how Aunt Harry could take it all without even batting an eye, as she faced him standing soldier-straight and arms crossed.

"Let's get this out of the way," Aunt Harry started. "I'm not here to train you. We haven't got the time for that."

"Why are we here, then?" asked Harry, an arm over his nose.

"We're here to see how you'll react to explosions," said Aunt Harry. "And, as much as possible, make you get used to them."

Harry doubted anyone could get used to explosions, least of all him. Aunt Harry smirked at Harry, as though she knew what he was thinking.

"Trust me, you can get used to anything," she said. "In some parts of the Middle East, no one even blinks unless it's their own house that got hit."

Then Aunt Harry turned heel and walked away. Harry soon found himself standing alone inside the building.

"Use everything you've got!" Aunt Harry shouted from somewhere. "And I do mean _everything_!"

"Wait, what am I supposed to be doing?" Harry hollered.

There was no answer. Harry felt his palms sweating and heart pumping as the silence dragged on. His brain churned with questions: was he supposed to stay here while bombs went off? Was he supposed to seek safety? Would he flip out if or when Aunt Harry set off whatever she rigged up? What would Aunt Harry do? Would she really set up _real bombs_? More importantly, what was _Sherlock_ trying to prove?

Harry eventually decided to seek better shelter, because as far as he was concerned, staying put where his enemy (Aunt Harry) knew where he was at was just nuts. But how was he to do that? The only thing Harry had to his advantage was Magic, but he wasn't allowed to use it during summer holidays. However, Harry learned from experience it was better to assume permission and ask for forgiveness later when Sherlock was in the picture. Besides, he had other options.

Harry took out his Invisibility Cloak and wrapped it around himself. As he did so, Harry wondered if Aunt Harry had those thermal goggles that let you detect living creatures via their body heat. Would those things still work in the light day? Harry had to assume that they could; better safe than sorry.

Harry pulled out his wand. He then paused for a moment as he tried to remember the incantation Hermione used to conjure her waterproof and portable bluebell flames. He came up blank. So he thought of a Latin word that best encapsulated what he wanted:

"_Inflamarae,_" he whispered.

White balls of fire appeared. Close enough, Harry thought, as he quickly magicked them into humanoid shapes.

Harry thought he heard someone swear from a distance as he tiptoed away. But before he could get too far, a series of small explosions on the ground followed his trail. Harry knew instantly Aunt Harry had detected him based on disturbances his feet left as he walked (John used the same tactic while they trained in Yorkshire). So Harry cast a spell that conjured large billows smoke. Aunt Harry's response to this was shooting rockets around the perimeter … all except one spot, where there was an ancient oak tree. Harry hurried over to there.

Harry stopped dead in his tracks once he got close. Tied around the massive trunk was something that looked a lot like a time bomb. Also half-buried around the tree were small metal boxes that were probably mines.

_Real EOD doesn't work like the movies_, said John's voice in Harry's head. _In the field, you don't mess around with wires. Instead you walk away, tell the guys where the bombs are from a safe distance, and the sniper takes them out._

Harry backtracked to the building. Once inside, he took out his wand and banished the bomb and mines. The moment he did so, Aunt Harry started firing at that spot. Clearly she was tracking all of her devises, somehow.

"All right, change of plans," Harry muttered. "Capture the enemy."

There really wasn't any other choice. He couldn't do anything while Aunt Harry was loose. But how could he, Harry, locate and disable Harriet Watson? Muggle she may be, Aunt Harry was a seasoned field operative. In almost all sense of the term, she was better equipped than Harry could ever be. How could he locate a hiding soldier, anyway?

It came to Harry almost immediately: _the rockets. _Harry studied the trail of white smoke they left. They seemed to originate in two places, in opposing sides. Unless Aunt Harry was a witch, she couldn't move between the two locations so quickly. Therefore she had backup (of course she did). So … should he get them both or just Aunt Harry? Who was her backup, anyway?

Then Harry noticed the smoke from his left was erratic, like it didn't know how to aim. Aunt Harry could probably do better, Harry thought, as he readied himself.

Harry quickly created a clone and cast the Disillusionment Charm on it. The semi-invisible clone headed to the left while Harry raced towards the right. More rockets followed. Harry tried to clear the resulting smoke with another made-up spell. But instead of clearing the smoke, the spell conjured a flock of flamingos.

Harry heard a voice swearing up a storm as the flamingos flew to and fro. Figuring the voice belonged to Aunt Harry, Harry headed towards it, dodging debris all the way.

He found a makeshift tower just outside the bush. The person who was inside appeared not to notice his presence, as no one came out to investigate.

Harry tiptoed to the back as another rocket flew out from the top of the tower. The tower, it turned out, was actually a braced wall with a raised platform and window. An unfamiliar woman wearing shorts and running shoes was manning the latter. She was not operating a rocket. In fact, there was nothing resembling a weapon on or around her.

Not wanting to take any chances, Harry used _Petrificus Totalus _on the stranger. Down went the woman, her arms and legs snapped together as she fell to the floor with a thud. Harry briefly wondered who she was as he walked over to the window where she used to stand.

The rockets stopped by the time Harry reached it. Everything went eerily quiet and still. Harry looked around, wondering where Aunt Harry was.

Suddenly Harry felt something fast whip past. His Invisibility Cloak fluttered, revealing Harry for a moment. Instinctively, Harry scrambled for cover. Not a moment too soon— the tree behind him shattered with bullet holes.

"What the hell! Those are real bullets!" Harry shouted as he crawled away.

Harry left the braced wall and made his way to the opposite direction. There were no towers or walls there … Just Aunt Harry in the growth. Not that Harry could see her; she was better than that.

Harry pointed his wand in the general direction of the growth.

"_Homenum Revelio_," he muttered.

A place he completely didn't expect glowed yellow. But before Harry could act on this information, Aunt Harry burst out from the bush.

On the next conscious moment, Harry found himself on the ground and unable to breathe. Aunt Harry loomed on top of him, a wild look in her eye. Harry panicked as the vice-like grip around his throat tightened. Was she really going to kill him? Was he really going to die?

A pair of arms grabbed Aunt Harry from behind.

"Stop it, Harriet!" said Sherlock's voice. "That's enough!"

Aunt Harry stiffened. She remained as is—her right hand on Harry's throat and other drawn back—despite Sherlock's tugging. Despite his predicament, or perhaps because of it, Harry wondered just how strong Aunt Harry was. Sherlock could straighten a bent iron poker (he'd seen him do it), therefore was no slouch in the physical strength department.

Eventually the strong grip around Harry's windpipe loosened. As Harry gasped for breath, someone raised him to a sit and wrapped their arms around him.

"It's okay, you're okay, it's over," John's voice whispered above him.

Harry let out a shaky sigh and went limp. _John._ He was safe. It was over.

There was a scuffle. Harry looked up just in time to see Aunt Harry throw a punch at Sherlock, who blocked it.

"Calm down!" Sherlock grunted as Aunt Harry followed the punch with a powerful jab. "What's the matter with you?!"

"How the"— Aunt Harry spewed a string of obscenities Harry had never heard used in such a combination — "did you raise your kid!?"

"We taught him to defend himself," Sherlock replied, fists up like a boxer.

"Don't f— with me!" Aunt Harry screamed. "You know how it works as well as I do!"

Sherlock frowned. John said nothing, but just held Harry tighter. Harry peered at his Aunt curiously.

" 'There are daring pilots and there are old pilots, but there are no daring old pilots'!" shouted Aunt Harry. "Your kid knows war! He didn't f—ing lose his head, and f—ing found me in five minutes! And those flamingos! Where the f— did they come from? How the f— did he turn completely invisible?! _Seriously, w__hat the f— is your kid!?_"

No one said anything in the silence that followed the tirade. All one could hear was Aunt Harry's heavy breathing. Then, without warning or any noise, Mr. Lestrade and Mr. Jason appeared out of thin air.

John looked away.

"Harry, I'm sorry."

Harry twitched. At the same time, Aunt Harry frowned.

"What?" she said. Oddly, she spared no attention to the two wizards behind her.

"I'm so – so sorry," said John, grimacing as though in pain.

Harry looked at John, at Aunt Harry and back, his eyes growing larger. Aunt Harry started to look alarmed.

"Johnny? What are you…"

She didn't finish. Mr. Jason cried:

"_Obliviate!_"

-oo00oo-

**Final Notes**: Talk about O'Toole's Corollary (i.e. Murphy Law is too optimistic). Since the last update, I pulled a series of 60-70 hour workweeks due the project losing all but two incumbents (which includes yours truly). Some good things came out of the debacle, however: I was awarded employee of the month, and was able to use my performance as leverage to improve my work situation (I can work remotely!)

I confess I had no motivation to resume writing after the three month mark, which was when things started to calm down. It soon became clear waiting for the right moment was an exercise in futility. So I made the command decision to start scribbling about two weeks ago. This meager chapter is the result.


	7. Inconstant Vigilance

**A Study in Magic: The Application  
**by _Books of Change_

**Warning/Notes**: This is the sequel to A Study in Magic, which is a BBC Sherlock and Harry Potter crossover AU posted here. The HP timeline and BBC Sherlock's timeline was shifted forwards and backwards to match up. One major BBC Sherlock character's gender was changed for the sake of the plot. Readers beware!

* * *

Chapter Six: Inconstant Vigilance

Harry screwed his eyes shut and waited for something to happen. When he was convinced there was nothing particularly wrong or different about him, he opened them again. The first thing he saw was Mr. Lestrade putting an unconscious Aunt Harry to a magical stretcher.

"Why d'you do that?" Harry asked.

"Do what?" asked Sherlock.

"Obliviate Aunt Harry," said Harry.

"It's obvious, isn't it?" said Sherlock. "Magic is need to know only. Harriet need not know."

Harry's immediate thought to this was: _says who_? He chose not to voice this, however, and instead asked:

"So what are you going to tell her?"

"Nothing," said Mr. Jason. "As far as your Aunt is concerned, today didn't happen."

Harry wondered how Aunt Harry was going to account for the lost hours when she woke up. He devoutly hoped she wouldn't blame it on drinking. Not for this case. It just didn't feel right.

"Why did she act like that?" Harry asked. "The last thing … Was it part of the test?"

"Of course not," scoffed Sherlock. "You were so good Harriet instinctively fell into battlefield mentality. Obvious."

Harry mouth fell open. Mr. Jason turned red, and Mr. Lestrade planted both hands on his face.

"Yes, Harriet might've gotten carried away," said John with a hard tone and a stony face. "It happens in this sort of setting. Speaking of which, _Sherlock_," John rounded at Sherlock, who started striding away, "Pick your tombstone. You're a dead man tonight!"

Sherlock broke into a dead run, John close on his heels.

"I'm too old for sh!te," Mr. Lestrade complained.

"Says the man who agreed to it," said Mr. Jason. "By the way, Harry, did you really mean to conjure those flamingos?"

"No," said Harry. "I wanted to make the smoke go away. I didn't know the actual spell for it, so I made it up."

"Did you say '_Depulso__ Flamma' _or '_Depulso Fumus_'?" Mr. Jason asked.

"Uh, I think _fumus_," said Harry.

Mr. Jason smiled.

"They're both wrong. You can't really banish smoke or fire because it doesn't have a solid form. Putting them _out_, now, that's perfectly possible. I suggest _Ventus_." He patted Harry's shoulder consolingly. "I have to say: you've got a good ear for incantations. I hate memorizing them, too. You'd think Flitwick would teach us how spells are put together, rather than make you learn them by rote."

"Yeah," said Harry quickly. "So is there some kind of rule?"

Mr. Jason shrugged.

"I don't know. I don't remember learning it. You should ask Flitwick or McGonagall. Or that your teacher friend of yours; what's his name—"

"Remus Lupin," said Harry.

At that moment, John and Sherlock returned, John dragging Sherlock by the ear.

"So how are we keeping Harry's magic use from the Ministry of Magic? Did you get a waiver?" John asked.

"The MOM doesn't give out waivers, not when they've got magic parents who can do the enforcing," Mr. Lestrade replied.

"And we know how well that goes," said Sherlock, as he twisted himself out of John's grip. "So how are we hiding it, then? It's not as if you or Jason were following Harry around."

"We have Susan," said Mr. Jason.

"Susan who?" asked Sherlock.

Mr. Jason looked around and started to look increasingly alarmed.

"Did you stun someone during the exercise?" he asked to Harry.

"Er, yes?" said Harry.

Without another word, Mr. Jason hurried away towards the direction of the braced wall.

"So who's Susan?" asked John.

"Susan Lusichi; Muggle-born; a late-bloomer of magic like yours truly," said Mr. Lestrade, sounding as though he was reciting a police report. "She grew up in Northern Kenya, then moved here as an adult … Kenya doesn't have the kind of magic education system we have."

"But I saw African wizards at the world cup," said Harry.

"And of course Africa is a single monolithic entity," Sherlock drawled.

"I'm not saying they don't have _anything_," said Mr. Lestrade, sending a withering glare at Sherlock. "Muggle-borns tend to fall through cracks more readily in certain parts of the world. Not because of some pure-blood agenda, necessarily, but some countries just don't have what it takes to pick them all up."

"But what is the true significance of Susan?" asked Sherlock. "Some Muggle-borns are false negatives, or are victims of Magic Culture, or the lack thereof. Obvious. Why is this Susan different than you?"

"She's a professional ultramarathon runner," said Mr. Lestrade simply.

There was a beat.

"Oh," said John and Harry.

"_Ah_," said Sherlock.

"Are you talking about me?" said an unfamiliar voice.

"Obviously," Sherlock sneered, without missing a beat.

Harry gazed at Susan Lusichi, who turned out to be a skinny young woman with mocha-coloured skin. He quickly noticed a lot of details about her he couldn't believe he missed the first time. For one thing, she was wearing a long, bright-red sleeveless shirt and a multitude of beaded necklaces. She also had prettiest legs and shapeliest body Harry had ever seen.

Mr. Lestrade explained how he met Susan at John's prompting. He'd been invited to speak at a conference for witches and wizards who'd discovered their magic late in life, and there he was introduced to a small group of professional runners, one of which was Susan.

"Why did it take you so long to notice it?" asked Sherlock. "I was given to understand long-distance running significantly increases one's magic capacity."

"When you live near the bush, you don't really notice it," Susan said. "I would've never noticed had not I wanted to go to school and learn about computers. But I did, and so my mother sent me to the city, where her sister lives."

"Did all electronics and power lines in your vicinity explode on your way there?" asked Sherlock.

Susan nodded, miming with her hands and mouth: "boom, boom, boom, boom …"

"All of the runners I met had a fifty meter electromagnetic dead zone," Mr. Lestrade explained. "Susan's spans a good hundred meters, she has so much magic. So there's no chance in hell the Ministry will be able to detect Harry using magic when she's around."

"Does this mean she's the most powerful witch in the world?" said Harry, genuinely impressed.

"In terms of raw power, probably," said Mr. Lestrade.

"So what? I can't control it," said Susan. Then with a sorrowful voice, she said: "If there is a way to get rid of it, I would."

"Why?" John asked.

"I can't call my family," said Susan. "I can't tell my people I'm a witch. They would interpret it the wrong way. I still want to learn about computers, but all I can do is run." She sighed. "It's very lonely."

Harry felt his throat tighten so much that it left him speechless. At the same time, he was filled with a strong desire to say or do something that would make Susan thinking better of magic. But what could he possibly say? How could someone who loved Magic and thought it was something wonderful, understand someone who experienced the worst sort of loss because of Magic?

"Time to go home," Sherlock announced, turning his back on everyone. "I had enough of this."

Harry, John and Mr. Lestrade prepared to leave shortly afterwards. Mr. Jason offered to Apparate Aunt Harry and Susan to their respective flats, and assured Mr. Lestrade and John that he didn't need help.

Harry felt his legs give out as soon as he got into Mr. Lestrade's car. He also felt as though he was suffering a bout of flu; he couldn't stop shivering, and his teeth chattered.

"That happens after a firefight," said John, as she wrapped Harry in a warm blanket. "It's normal."

"There's nothing normal about this," Harry groused. Then, without thinking, he asked: "Why didn't you tell Ms Lusichi about your blood transfusion, Mr. Lestrade?"

Mr. Lestrade butted his forehead against the stirring wheel. Sherlock sighed heavily.

"Must you ask such stupid questions?" Sherlock groaned.

"Shut up, your kid had a rough day," said Mr. Lestrade. To Harry he said: "Say LV learns about how I lost magic. What would he do?"

There was a short, but terrible pause.

"He'd use it on the Muggle-borns and his enemies," Harry muttered.

"That's why we keep mum," said Mr. Lestrade sternly. "Trust me, I feel shitty about it. Susan should have a choice, and we're not giving it to her."

"I suppose it wouldn't help us if she loses her magic, since we could potentially transfer some hers to Harry for better use," Sherlock remarked.

Mr. Lestrade stepped hard on the brakes, making everyone jerk forward.

"Sherlock, I suggest you shut up _right now_ so I can pretend like you didn't say that!" Mr. Lestrade snarled.

"But it's a—"

"Shut up … just shut up right now!" Mr. Lestrade snapped.

Sherlock, miraculously, closed his mouth.

Mr. Lestrade resumed driving in heavy silence. Sherlock turned to John and mouthed: _Bad?_

_Off the charts_, John mouthed back.

-oo00oo-

Mr. Lestrade dropped off Harry, John and Sherlock in front of Speedy's and drove away. Much to Harry's mortification, John and Sherlock had to half-carry him inside 221B because his legs refused to cooperate. Once inside the living room, Sherlock and John engaged in a staring match. Harry, who knew better than to interrupt when his parents were in a combative mood, kept quiet and futilely willed himself to move.

"So?" said John, at last, breaking the impasse.

"You're not angry with me," Sherlock remarked.

"Well, no," John said matter-of-factly. "An untrained person in Harry's situation will try to keep vigil, and quickly get tired. So we need to make sure he knows how to react. Preparation is easier than vigilance. I get it."

Something tense in the room seemed to vanish like a cloud after this statement. Harry certainly felt relieved, though he couldn't say why.

"…So you get it," muttered Sherlock. "You get it," and as he turned away it seemed to Harry that he was more moved by the show of simple faith and understanding than he had ever seen him. A moment later Sherlock was back to his normal self.

"It makes a considerable difference, having someone on whom one can thoroughly rely," he said. "Take note of that, Harry."

"Sure," said Harry. "So how do you want me to prepare?"

"I don't know, you tell me," said Sherlock.

"How can _you_ not know?" asked Harry, dismayed and more than a little astonished.

"We're _Muggles_," said Sherlock impatiently. "We don't _get_ magic. Not in a meaningful way. You do."

"But…!" Harry protested.

"Think," said Sherlock, cutting him off.

"Think, _what_?!" Harry cried.

"Just think!" barked Sherlock . "Haven't I taught you how?"

Harry knew from Sherlock's tone that he had been dismissed. So Harry stomped upstairs … or rather, tried to. His upper body leaned forward and his lower body stayed put, which resulted in him face-planting hard on the hearth rug. Harry stayed there for a while, twitching with righteous indignation, until John gave him some Pepper-up Potion. Harry felt his strength return to him after he'd gulped down the Peppery liquid, so he picked himself off the floor, stomped noisily to his bedroom, and, almost in spite of himself, paced around inside his room, deep in thought.

How was he supposed to prepare? Harry wondered, as he marched up and down the length of his room. Lord Voldemort could strike whenever he wanted, if he was so inclined, whereas Harry had to be on the lookout every day and every hour just in case. Was he supposed to invent a magical detection system, then? How long would it take for him to make one? Could there be an existing solution? Those Dark Detectors he'd seen in Mad-eye Moody's office, could they be useful? Or maybe there was something in Fred and George's chest …

Harry went down that thread of thought for several hours. As he reviewed what he knew about Dark Detectors and Fred and George's inventions, Harry realized all of them had the same flaws: they could be disabled, and at best would only work if he knew every single person LV would use. If LV decided to use an agent he wasn't aware of, they wouldn't get detected, and his system would fail. Putting up a system that had the same consequences as him doing nothing when it failed was useless.

…Or was it? The last time they knew where Lord Voldemort would strike, but didn't know when or how, which was the time they knew the Department of Mysteries had something LV wanted, they purposely created a situation where LV couldn't resist infiltrating in person. Thus the Intrusion Detectors in the Department of Mysteries merely alerted them when LV did show up. Could he do something like that?

Sirius hollered at Harry to join for dinner at this point. Harry ignored the calls in favour of bringing his latest idea to its logical conclusion:

Harry had to assume if he was going to lure Voldemort anywhere, it would have to be Hogwarts. It was, after all, the most plausible place something powerful may exist. However, LV may be convinced Hogwarts had nothing to offer him right now. Even if Harry did somehow convince LV Hogwarts had something he wanted, what was he to do after he came? He supposed he had Dumbledore, but LV may choose to show up only if Dumbledore was out of the picture (Harry tried very hard not to think what this may mean). One-on-one combat between him and LV was out of the question.

"It's not as if I could kill him, even if I knew how," Harry muttered to himself. "He can't die unless we destroy all of his soul jars."

Then it hit him.

Voldemort could not be destroyed without destroying all of his Horcruxes. Therefore the Horcruxes were things LV would want to protect at all costs. Dumbledore and Mr. Shin were hunting down the Horcruxes, and the last he heard, the two wizards had destroyed three out of potential six (a diary, ring and cup). Harry could count on Dumbledore to find the rest, and no doubt LV would think the same if only he knew what Dumbledore was up to. What if he, Harry, convinced LV that they had discovered his Horcruxes and were keeping them in Hogwarts? Better yet, what if everyone focused their attention on finding and destroying the Horcruxes, so when they alerted LV, they would be telling the truth? Come what may, Harry would be as ready as he could ever be at that point.

Harry immediately grabbed his phone and dialled Julia Lestrade.

"Julia, I need your help," he said without a pause.

"Sure, what?" said Julia.

"I need you to learn how your Grandpa finds LV's soul jars," Harry said.

-oo00oo-

**Final Notes**: I could've sworn this chapter was longer than the previous one. It certainly felt that way when I was writing it. Hopefully I'll get back to writing 4000 to 5000 words like I used to…


End file.
